Planar-style gaskets employed in the automotive arena including air intake manifolds have traditionally been formed of composite gasket body materials having beads. The beads are generally positioned along a peripheral edge of the gasket body. When the gasket is compressed between two joining surfaces such as an engine head and engine block, the beads also compress and form a seal between the joining surfaces. The seal prevents the transmission of fluid or gases and with the example of the air intake manifold gasket, the seal prevents the transfer of an air/fuel mixture. A traditional material used to form the sealing beads is silicone rubber. Silicone rubber has achieved a perception in the automotive industry of superior sealing results and is relatively inexpensive when compared to other alternative materials.
In the past, manufacture of gaskets with silicone rubber beads have been time consuming and expensive. Often, spacing between two mating surfaces is greater than the thickness of the gasket body and accordingly, the height of the sealing bead must match this distance in order to provide an effective seal. The most common technique for applying the silicone rubber bead to the planar surfaces of the gasket body is by screen printing. One pass of the screen typically deposits 0.007″ to 0.008″ of material on the body. In order to fill the distance between the mating surfaces, approximately three passes must be made. Each subsequent pass deposits a slightly narrower bead of the rubber and requires a different size screen. The repetitive passes of the screen printing process and the constant change of screen sizes becomes expensive and time consuming.
A further disadvantage of traditional gaskets having sealing beads is seal failure resulting from the rigorous pressure and high temperature demands of modern engines. Once the bead is compressed under these conditions in may burst or tear. The seal will fail, thereby leaking fluids and gases.
A gasket with improved sealing capability and more convenient manufacture is needed particularly with air intake manifold applications; one employing improved sealing materials, and one involving less time consuming and less expensive manufacturing processes.